The present invention relates to a filter medium for cake-forming filtration processes.
In general, woven or needle-felted filter media are known, which are used for cake-forming filtration. Many varied requirements are made on such filter media. In particular, they must have openings such that those particles which are to be filtered out of the suspension are held back by the filter medium. A cake is then formed from these particles on the filter medium, while the liquid passes through the openings therein.
Modern process engineering makes it necessary to frequently filter extremely small particles out of a suspension. The hitherto known filter media, e.g., woven or needle-felted filter media, are difficult to produce with openings smaller than 10 um and this is certainly not possible when the openings are below 1 um. It is fundamentally possible to use filter membranes for such purposes. However, these membranes cannot meet the robust mechanical demands made in filtration technology. The filter medium is exposed to severe mechanical stresses, particularly during the removal or release of the filter cake. Filter membranes are unable to withstand these stresses to the desired extent.
The problem of the prior art is to provide a filter medium of the aforementioned type which, in the case of a particularly robust construction, is suitable for the filtration of suspensions containing extremely fine particles.